Solar and Planetary Evolution. 73 



alescc with suus, and worlds with worlds, to be thrown back again 

 and again with diminishing force, till at last the whole universe 

 «nds as a dead, black, monster furnace-slag, is to reason fi-om in- 

 sufficient data and tome to improbable conclusions. An incalcu- 

 lable periotl of time has already gone by, and the linite energy we 

 know of should long ago have been degraded and escaped. The 

 universe sliould already have been a slag; but it is not. Substance 

 Y>er sc, in cycle of experience from invisibility to matter, is much 

 more likely to have a rhythm of contraction and union with ex- 

 pansion and disunion, through inherent forces, than worlds are 

 likely to rush into each others' embrace and be cast off again. 

 Let the physical cause of cohesion cease, and there will no longer 

 be such a bond. How do we know that cohesion is uncaused ? 

 How do we know that gravity has not a physical condition pro- 

 ducing it ? Dissolve that condition and where is gravity ? Ke- 

 move gravity, cohesion and affinity, by cvohing out of the physi- 

 cal conditions producing them, and all things will gradually melt 

 into the impalpability of the universal ether from whence they 

 first came. Here they can once more commence their career, 

 while the law of continuity is allowed to pursue the even tenor of 

 its way without that bugbear of every embryo science, cataclysm. 

 Natura nonfacit saltuin. 



Pkofkssoe r. H. VAX DER Weyde : — 



I do not think that the theory of Laplace, so clearly explained 

 and illustrated by the lecturer, properly accounts for the forma- 

 tion of our solar system. When motion originates from the cen- 

 ter of a mass, and is communicated outward, as in Laplace's 

 theory, the inside of each fluid ring, on separation, will move 

 more rapidly than the outside; and when the ring breaks, the di- 

 rection of rotation of the resulting globes will be opposite to that 

 of the central mass. This is the reverse of what we see in our 

 solar system. We have, however, only to conceive of matter dis- 

 persed through space in a highly rarified state, — dispersed un- 

 equally as regards quantity and quality, — and then the operation 

 of the simple law of gravitation is sufficient to explain the forma- 

 tion of all solid, licjuid or gaseous masses forming our solar sys- 

 tem. 



We have to start with nebulous matter diffused through space, 

 and mutually acting and acted upon by the imiversal force of grav- 

 itation. The reaction of this force, commencing from the outside 

 and acting inward toward centers of condensation, would perhaps 



